Participants with unilateral patellar tendinopathy and symptoms lasting three months or less were recruited. Biopsies were taken from the proximal regions of the tendinopathic and contralateral patellar tendons. Proteins were isolated, digested, and prepared for data-independent acquisition liquid-chromatography mass spectrometry. Peptide and protein abundance were calculated and subjected to two-way ANOVA with factors symptom status (symptomatic or non-symptomatic) and symptom duration (one, two, or three months).